arXiv:2610.19977v1 Announce Type: new Abstract: Facial gestures can enable access for people with motor impairments (PwM), yet recognizers may not reliably interpret individual facial movement patterns. Existing approaches either constrain agency by requiring predefined templates or impose repeated calibration, data collection, and computation through user-specific retraining. We present AdaptaFace, an input-level compatibility layer using bounded, proxy-dependent adversarial perturbations to translate user-compatible gestures into inputs for an unchanged facial action unit (AU)-based recognizer. Designed around six personalization principles informed by interviews with 12 PwM, AdaptaFace supports both recognition enhancement and gesture vocabulary extension. In a within-subject study with 16 participants, AdaptaFace increased task completion from 59.7% to 90.5% and reduced workload from 5.61 to 4.21. Offline validation showed strong steering with aligned perturbation generation and evaluation but weaker cross-recognizer transfer, defining the approach's boundary. These findings frame adversarial assistance as input-side accessibility mediation for personalized facial-gesture interaction.